The hydrogen ion concentration in the given substances can be calculated by using the given relation: pH = –log [H+]
(i) pH of milk = 6.8 Since,
pH = –log [H+]
6.8 = –log [H+] log
[H+] = –6.8
[H+] = anitlog(–6.8)
= 1.5×19–7 M
(ii) pH of black coffee = 5.0 Since,
pH = –log
[H+] 5.0 = –log
[H+] log
[H+] = –5.0
[H+] = anitlog
(–5.0) = 10–5 M
(iii) pH of tomato juice = 4.2 Since,
pH = –log
[H+] 4.2 = –log
[H+] log
[H+] = –4.2
[H+] = anitlog
(–4.2) = 6.31×10–5 M
(iv) pH of lemon juice = 2.2 Since,
pH = –log
[H+] 2.2 = –log
[H+] log
[H+] = –2.2
[H+] = anitlog
(–2.2) = 6.31×10–3 M
(v) pH of egg white = 7.8 Since,
pH = –log
[H+] 7.8 = –log
[H+] log
[H+] = –7.8
[H+] = anitlog
(–7.8) =1.58×10–8 M